<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <script>
        /* 
        indexOf()   //查询数组某个值的下标
        slice()    //第一个参数：从数组中某个值的下标开始  第二个参数:查询的个数
        includes()   //判断数组是否包含某个值
        */
        var arr=['html','css','javascript']
        var app=[1,2,3,4,5,6]
        console.log(arr.indexOf('css'))    
        console.log(app.slice(0,3))
        console.log(arr.includes('javascript'))
    </script>
</body>
</html>